A new study from the Liberty Mutual Research Institute for Safety ties these topics together, showing the dangers of driving following night shift work.

In the study, scientists examined the impact of night shift work on drowsiness and driving performance using real vehicles on a closed test track—as opposed to a driving simulator—and actual night shift workers.

Sixteen night shift workers each completed two driving sessions: one after 7.6 hours of sleep and no night shift work, and the other after working a night shift. During each session, the researchers collected objective and subjective measures of drowsiness and driving performance.

The scientists found that more than a third (nearly 40%) of drivers who operated a vehicle after working the night shift were involved in one or more near-crash events. The same drivers, with normal sleep the night before the test, had zero near-crashes. And the differences between the post night shift and post sleep conditions became more pronounced after driving for more than 30 minutes.

Following the night shift, drivers experienced the following, which are indicative of the transition from wakefulness to sleep: